In the Open Systems Interconnection (OSI) communications
model, the application layer provides services for an
application program to ensure that effective communication
with another application program in a network is possible.
The application layer is not the application itself that is
doing the communication. It is a service layer that
provides these services:
application layer is then seventh layer of the open system
interconnection.it is the layer which is closely related
with the user. user can run any application program. the
proto col that works on application layer are ftp(file
transfer protocol)used for transfering files,telnet for
remote access,dhcp(dynamic host configration protocol)used
for assigining ip address automatically,http(hyper text
transfer protocol) ,and udp(user data granm protocol)
We find 7 layers on the Source Side and 7 layers on the
Destination side and the data transfer from Source to
destination is called as OSI Model (Open System
InterNetwork).The 7 layers are as follows on the Source
Similarly the viceversa of the layer from desecding order
is as 7,6,5,4,3,2,1 on the Destination side.
Application layer is the layer where the file is stored in
the form of an extension (eg:.pdf,.txt,.jpeg etc).
open system intercoonect is osi and brought by iso in 1974. it has 7 layers . it is guide or a refrence model for realtime tcp/ip layer.
application layer is the layer 7 of OSI. IT IS THE IDENTIFYING THE NETWORK INTERFACE TO USERS . THIS IS DONE THROUGH PORTS . A PORT IS AN ENTRY AND EXIT POINT . THE PROTOCOLS THAT ARE WORKING IN THIS LAYER IS HTTP(80),TELNET(23),FTP(21),SMTP(25),PING(7),POP3(110),DNS(53),DHCP(67,68)
Application layer is mainly used by the application
programs. The main functionality of the application layer is
to identify the application program requested communication
partner and establish a communication channel with it.
Ex: If Internet Explorer browser (Application software)
needs to upload to an FTP server it does so by FTP protocol.
Examples of Application layer protocol are HTTP,SNMP,SMTP,TELNET